Download Schwannoma of the floor of the mouth

Schwannoma of the floor of the mouth
YADRANKO DUCIC,
MD, FRCS(C), FACS,
Dallas and Fort Worth, Texas
S chwannomas, or neurilemmomas (as they are
occasionally called), typically present as firm, encapsulated masses with a solid to partly cystic
gross appearance. These benign neoplasms originate from Schwann cells, which develop during
the fourth week of gestation during the ectomesenchymal detachment of the neural crest. They
subsequently form an envelope around extracranial nerve fibers, providing them with a layer of
myelin to improve the propagation of signals
along the nerves. Schwannomas may arise anywhere in the body, but they have an affinity for the
head and neck region and extremities. In fact, 25%
of all schwannomas arise within the head and neck
region.1 However, only a few cases of such tumors
have occurred in the oral cavity.2-5 All previous
oral cavity schwannomas had prominent involvement of the tongue, which facilitated diagnosis in
those patients. In this case report, I present an
isolated floor of mouth lesion with subtle clinical
findings.
CASE REPORT
A 42-year-old male presented for evaluation of
progressively worse snoring for 1 year. He did not
report any odynophagia, dysphagia, or dysphonia.
His surgical and medical history was not significant; in fact, he was in excellent health otherwise.
Specifically, he had a negative family and personal
history of any neurologic disorders or neoplasms.
Examination revealed that he was a well-nourished male in no apparent distress. He did have
some fullness in the floor of the mouth and subFrom the Department of Otolaryngology–Head and Neck
Surgery, University of Texas Southwestern Medical Center
and the Division of Otolaryngology and Facial Plastic
Surgery, John Peter Smith Hospital.
Reprint requests: Yadranko Ducic, MD, FRCS(C), FACS,
Director, Otolaryngology and Facial Plastic Surgery, John
Peter Smith Hospital, 1500 South Main Street, Fort Worth,
TX 76104; e-mail, [email protected].
Otolaryngol Head Neck Surg 2003;129:144-6.
Copyright © 2003 by the American Academy of Otolaryngology–Head and Neck Surgery Foundation, Inc.
0194-5998/2003/$30.00 ⫹ 0
doi:10.1016/S0194-5998(03)00483-2
144
mental region that was soft in consistency. Nasopharyngolaryngoscopy revealed the presence of
retrodisplacement of the base of the tongue with
narrowing of the airway at this level, as evidenced
on Müller’s maneuver. A CT scan of the neck,
performed to further evaluate the fullness in the
floor of mouth, revealed a large cystic lesion consistent with a possible ranula (Fig 1). An incidental note was made of a large, calcified left thyroid
mass. The patient subsequently underwent a left
hemithyroidectomy that revealed a benign adenoma. A submental approach was used to gain
access to the patient’s floor of the mouth lesion.
After the mylohyoid and anterior digastric muscles were split, a firm, encapsulated mass with no
apparent attachment to the lingual or hypoglossal
nerves was removed in toto through careful dissection. The patient’s postoperative course was
uneventful, with resolution of his snoring and normalization of the positioning of the base of the
tongue to a more anterior location. The pathologic
specimen was consistent with a benign nodular
schwannoma, measuring 6.5 cm in maximal dimension. On microscopic examination, the specimen was noted to be composed of spindle cells
with regular, elongated nuclei and moderate
amounts of fibrillary eosinophilic cytoplasm (Fig
2). The nuclei palisaded and alternated with acellular fibrillary areas, giving rise to well-defined
Verocay bodies. The interlobular septa contained
similar spindle cells within a myxoid stroma.
DISCUSSION
Schwannoma of the oral cavity is an exceedingly rare entity. The case described here illustrates the potential for an indolent progressive
course with subtle clinical findings. The diagnosis was not suspected until microscopic examination had been completed. There are 2 distinct patterns of schwannoma, namely, Antoni A
and Antoni B. The former is characterized by a
highly cellular pattern organized in palisading
fascicles with little stromal matrix. By contrast,
the Antoni B pattern exhibits a less cellular,
more irregular growth pattern within a myxoid
Otolaryngology–
Head and Neck Surgery
Volume 129 Number 1
DUCIC
145
Fig 1. Preoperative axial CT scan of the neck demonstrates an apparent cystic lesion occupying much of the floor of the
mouth.
Fig 2. (A) Gross appearance of a completely excised 6.5-cm tumor. (B) Photomicrograph demonstrates the typical
palisading nuclei arranged around acellular fibrillary areas that is typical of schwannomas (hematoxylin-eosin stain,
original magnification ⫻40)
Otolaryngology–
Head and Neck Surgery
July 2003
146 DUCIC
stroma. Schwannomas may not be accurately
diagnosed or suspected preoperatively unless
the patient has a personal history of such a
tumor or there is a personal or family history of
other neural lesions, as in von Recklinghausen’s
disease. Schwannomas are generally slowgrowing lesions with little potential for malignant degeneration or recurrence. Obviously, the
natural history of oral cavity schwannomas has
not been fully elucidated because of the paucity
of patients with this diagnosis. Complete surgical excision appears to be the treatment of
choice.
REFERENCES
1. Katz AD, Passy V, Kaplan L. Neurogenous neoplasms of
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2. Pfeifle R, Baur DA, Paulino A, et al. Schwannoma of the
tongue: report of 2 cases. J Oral Maxillofac Surg 2001;
59:802-4.
3. Chiapasco M, Ronchi P, Scola G. Neurilemmoma
(schwannoma) of the oral cavity. A report of 2 clinical
cases. Minerva Stomatol 1993;42:173-8.
4. Gallesio C, Berrone S. Schwannoma located in the
tongue. A clinical case report. Minerva Stomatol 1992;
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5. Nakayama H, Gobara R, Shimamoto F, et al. Ancient
schwannoma of the oral floor and ventricular portion of the
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